如何从php action更新数据库数量

$servername = "数据库服务器地址";
$username = "数据库用户名";
$password = "数据库密码";
$dbname = "数据库名";

// 创建连接
$conn = new mysqli($servername, $username, $password, $dbname);

// 检查连接是否成功
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

$product_id = 1; // 要更新数量的产品ID
$new_quantity = 10; // 新的数量

$sql = "UPDATE products SET quantity = $new_quantity WHERE id = $product_id";

if ($conn->query($sql) === TRUE) {
    echo "数量更新成功";
} else {
    echo "更新失败: " . $conn->error;
}

$conn->close();